Ice Therapy Machines

Hello, group! I’m new here. I bought an ice therapy machine to use after my TKR only to find out my doctor doesn’t approve of them. He won’t give me any guidance on how long on and how long off to use it, how often, etc. All I can find online is follow your doctor’s recommendations. Anybody use one and if so, how did you use it? Can’t find any negatives about it. Had 3 therapists tell me they’re great. But they work for the hospital/doctor, so….
Thanks!